Missing Dollar Puzzle

The Puzzle: Three friends check into a hotel. The room costs $30**, so they each pay **$10.

• Later, the clerk realizes the room was only $25.
• He gives $5 to the bellboy to return to the friends.
• The bellboy, not knowing how to divide $5 by three, decides to give **$1** to each friend and keeps $2 for himself.

The Deception:

• Each friend paid $10 and got$1 back, so they each paid $9.
• Total paid = 9 × 3 = $27.
• The bellboy kept $2.
• $27 +$2 = $29.
• Where is the missing $1?

1. The Flaw in the Logic

The mistake is in adding the $2 to the$27.

• The $27 is what the friends spent.
• Inside that $27, **$25** is with the hotel and $2 is with the bellboy.
• The **$3** they got back makes the full$30.

2. Correct Equation

• Total Paid ($27) = Hotel ($25) + Bellboy ($2).
• You shouldn’t add the $2 to the$27; you should subtract it to see where the money went!

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Interview-Focused Questions

Key Takeaway

Always verify the Direction of Flow. Money (or data) must always balance out if you follow the “Source” and “Sink” correctly.